As an example of the electronic component which uses dielectric films, the thin film capacitor, the thin film filter for high frequency or the like can be listed. These components are widely used as electronic components with small sizes and high performance. It is required that these components should have a higher capacitance, a small change on the electrostatic capacitance with respect to temperature and also should have excellent voltage resistance against a high voltage. Recently, as the devices with high functions such as the smart phones and the notebooks are to be further subjected to the downsizing and performance improvement, the same requirements to the electronic components also become stricter.
Based on such a requirement, for example the thinning of the dielectric film of the thin film capacitor is continuously progressing. If the film becomes thinner, the capacitance of the capacitor can be increased. However, on the other hand, the voltage resistance against a high voltage will deteriorate so that the desired property cannot be obtained.
For example, the amorphous SiOx film is usually used as the dielectric film for the DRAM capacitor of the semiconductor integrated circuit. However, when the same material is used in the thin film capacitor, the dielectric film should be further thinned to increase the capacitance as the relative permittivity of the amorphous SiOx is at a relatively low level of 2 to 3. In this respect, the thin film capacitor using the above mentioned material do not have good voltage resistance against a high voltage. Thus, in order to achieve the downsizing and the performance improvement of the thin film capacitor, it is necessary to replace the material with the dielectric material having a high relative permittivity, low temperature dependence of dielectric permittivity and a high withstand voltage.
With respect to, for example, the CaZrO3 thin film disclosed in Non-Patent Document 1 which is the material having a high relative permittivity, an amorphous Ca—Zr—O thin film is formed by changing the temperature of the thermal treatment after the formation of the CaZrO3 thin film. Here, the relative permittivity of the amorphous Ca—Zr—O dielectric is determined to be about 18, and the withstand voltage is about 3 to 3.5 MV/cm. However, the withstand voltage cannot be further increased.
Further, it is proposed in Patent Document 1 that the defect caused by the distortion at the interface between the metal and the dielectric can be inhibited by forming a thin film layer of the amorphous composite metallic oxides (the amorphous dielectric of the oxide of Ba and/or Sr and Ti) on a copper foil on which a metallic thin film layer containing at least one metal selected from the group consisting of Cr, Ni, Au and Ag is formed. In this respect, the insulativity can be ensured.